From: "Mickaël Salaün" <mic@digikod.net>
To: "Günther Noack" <gnoack@google.com>
Cc: "Mickaël Salaün" <mic@digikod.net>,
"Ada Smith" <adasmithgt@gmail.com>,
"Hungyu Lin" <dennylin0707@gmail.com>,
"James Morris" <jmorris@namei.org>,
"Josef Bacik" <josef@toxicpanda.com>,
"Paul Moore" <paul@paul-moore.com>,
"Serge Hallyn" <serge@hallyn.com>,
kernel-team@cloudflare.com, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: [PATCH 6/6] landlock: Fix capability restriction documentation
Date: Tue, 10 Nov 2026 21:24:34 +0100 [thread overview]
Message-ID: <20261110202436.2408244-7-mic@digikod.net> (raw)
In-Reply-To: <20261110202436.2408244-1-mic@digikod.net>
Some documented claims about LANDLOCK_PERMISSION_CAPABILITY_USE do not
hold for every capability check. Remove them instead of listing their
exceptions, and call it a permission instead of a hook.
Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Serge Hallyn <serge@hallyn.com>
Fixes: 97c8386f1d74 ("landlock: Enforce capability restrictions")
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
Documentation/security/landlock.rst | 8 ++++----
Documentation/userspace-api/landlock.rst | 8 ++++----
include/uapi/linux/landlock.h | 6 +++---
3 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/Documentation/security/landlock.rst b/Documentation/security/landlock.rst
index d81f1c2cd236..98c2e7139e8d 100644
--- a/Documentation/security/landlock.rst
+++ b/Documentation/security/landlock.rst
@@ -8,7 +8,7 @@ Landlock LSM: kernel documentation
==================================
:Author: Mickaël Salaün
-:Date: October 2026
+:Date: November 2026
Landlock's goal is to create scoped access-control (i.e. sandboxing). To
harden a whole system, this feature should be available to any process,
@@ -359,9 +359,9 @@ framework in ``log.c``, compiled under ``CONFIG_SECURITY_LANDLOCK_LOG``
(automatically selected by ``CONFIG_AUDIT`` or ``CONFIG_TRACEPOINTS``).
Audit records respect audit configuration, the domain's Landlock log
-flags, and ``LANDLOCK_LOG_DISABLED``. Tracepoints fire unconditionally,
-independent of these settings. The denial counter (``num_denials``) is
-always incremented regardless of logging configuration.
+flags, and ``LANDLOCK_LOG_DISABLED``. Tracepoints fire independently of
+these settings. The denial counter (``num_denials``) is
+incremented regardless of logging configuration.
Each denial tracepoint carries a ``logged`` field reporting the
audit-logging verdict: whether the denial would be written to the audit
diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst
index 3d45b956b640..d00e94d8ed37 100644
--- a/Documentation/userspace-api/landlock.rst
+++ b/Documentation/userspace-api/landlock.rst
@@ -8,7 +8,7 @@ Landlock: unprivileged access control
=====================================
:Author: Mickaël Salaün
-:Date: October 2026
+:Date: November 2026
The goal of Landlock is to enable restriction of ambient rights (e.g. global
filesystem or network access) for a set of processes. Because Landlock
@@ -532,7 +532,7 @@ acquisition via :manpage:`open_tree(2)` / :manpage:`fsmount(2)`. Namespaces
the process is already a member of when the domain is enforced are implicitly
allowed (the process could not continue running otherwise); rules describe
which new namespace types the process may acquire.
-``LANDLOCK_PERMISSION_CAPABILITY_USE`` gates every exercise of a capability
+``LANDLOCK_PERMISSION_CAPABILITY_USE`` gates the exercise of capabilities
after the domain is enforced, regardless
of how the capability was obtained (inherited credentials, ``CLONE_NEWUSER``
grant, ``setuid``/file-cap-bearing :manpage:`execve(2)`, etc.). Configuring
@@ -641,9 +641,9 @@ after a domain is enforced through user namespace entry or :manpage:`capset(2)`;
privileged sandboxes that did not set ``PR_SET_NO_NEW_PRIVS`` may also gain
capabilities through :manpage:`execve(2)` of binaries with file capabilities.
In all cases, :manpage:`capget(2)` will report the credential's capability sets,
-but any denied capability will fail with ``EPERM`` when exercised. Do not rely
+but any denied capability will fail when exercised. Do not rely
on :manpage:`capget(2)` to determine whether the policy permits a given
-capability; only the actual operation will return ``EPERM`` upon denial.
+capability.
Truncating files
----------------
diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
index 24510e5d8479..c9e4ce23778b 100644
--- a/include/uapi/linux/landlock.h
+++ b/include/uapi/linux/landlock.h
@@ -622,9 +622,9 @@ struct landlock_capability_attr {
* - %LANDLOCK_PERMISSION_CAPABILITY_USE: Restrict the use of specific Linux
* capabilities. A process in a Landlock domain that handles this permission
* is denied from exercising capabilities that are not explicitly allowed by a
- * %LANDLOCK_RULE_CAPABILITY rule. This hook is purely restrictive: it can
- * deny capabilities that the kernel would otherwise grant, but it can never
- * grant capabilities that the kernel already denied. Support added in
+ * %LANDLOCK_RULE_CAPABILITY rule. This permission is purely restrictive: it
+ * can deny capabilities that the kernel would otherwise grant, but it can
+ * never grant capabilities that the kernel already denied. Support added in
* Landlock ABI version 12.
*/
#define LANDLOCK_PERMISSION_NAMESPACE_USE (1ULL << 0)
--
2.56.0
prev parent reply other threads:[~2026-11-10 20:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-10 20:24 [PATCH 0/6] Fix Landlock mediation of commoncap's capability checks Mickaël Salaün
2026-11-10 20:24 ` [PATCH 1/6] landlock: Factor out capability denial checks Mickaël Salaün
2026-11-10 20:24 ` [PATCH 2/6] landlock: Mediate CAP_SYS_RAWIO for mappings below mmap_min_addr Mickaël Salaün
2026-11-10 20:24 ` [PATCH 3/6] landlock: Mediate CAP_SETPCAP for inheritable capabilities Mickaël Salaün
2026-11-10 20:24 ` [PATCH 4/6] landlock: Mediate CAP_SYS_ADMIN for the admin memory reserve Mickaël Salaün
2026-11-10 20:24 ` [PATCH 5/6] selftests/landlock: Test capability checks outside the capable hook Mickaël Salaün
2026-11-10 20:24 ` Mickaël Salaün [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20261110202436.2408244-7-mic@digikod.net \
--to=mic@digikod.net \
--cc=adasmithgt@gmail.com \
--cc=dennylin0707@gmail.com \
--cc=gnoack@google.com \
--cc=jmorris@namei.org \
--cc=josef@toxicpanda.com \
--cc=kernel-team@cloudflare.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=paul@paul-moore.com \
--cc=serge@hallyn.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®